Childlessness and Financial Transfers between Siblings Thomas V. Pollet (T.V.Pollet@ncl.ac.uk) Biological Sciences, University of Liverpool and School of Biology, University of Newcastle upon Tyne

Results The occurrence of giving financial help to a sibling and receiving financial help from a sibling in the sample was quite low (both below 2% ).

Childlessness, number of living siblings (less likely if more

siblings), interest given and initiative of contact (more likely if other

shows initiative/interest) were significant predictors of the likelihood

of giving money or valuables to a sibling (model: -2LogLikelihood (-

2LL)= 535.43; χ²= 44.77; df=6; p<0.001; Nagelkerke R²= 0.08; n=

4305). The other variables do not independently influence the

likelihood of giving to a sibling. Childless individuals are 2.62 times

more likely than ‘parents’ to have given financial help to their sibling

(Wald=11.34; p= 7.58·10-4). This while controlling for the effects of the

other proposed variables.

Age difference (more likely if larger age difference) , childlessness

of sibling, number of living siblings (less likely if more siblings) ,

childlessness, interest received (more likely if more interest was

shown) were significant predictors of the likelihood of receiving

money or valuables from a sibling (model: -2LL= 374.06; χ²= 32.51;

df=6; p<0.001; Nagelkerke R²= 0.08; n= 4305). Childless individuals

are 2,41 times more likely than ‘parents’ to have received financial

help to their sibling (Wald= 6.04; p= 0.014). If the respondent’s sibling

is childless, he or she is 2.41 times more likely to receive money or

valuables than when his/her sibling has children (Wald= 4.36; p=

0.037). Both effects were found while controlling for the effects of the

other proposed variables.

2.62 times more likely to give money/valuables if childless

2.14 times more likely to give money/valuables if childless2.41 times more likely to receive money/valuables if childless

Genetic relatedness did not (independently) affect financial transfers

between siblings. This can be explained, however, by the finding that

siblings who are not fully related interact significantly less. As such,

genetic relatedness is likely to influence, financial relationships

between siblings in an indirect way, via lower social interaction.

The majority of all financial relationships between siblings can be

described as ‘not given and not received’. If we examine only the cases

where a ‘financial transfer’ did occur, nearly 60% of all the financial

relationships can be described as ‘given but not received’ (n= 87).

There are no significant differences between parents and the

‘childless’, if a financial transfer did occur (χ²= 0.164; df= 2; p=

0.923).

Introduction

In modern societies, the proportion of individuals who remain childless

is rising.1 It has been argued that childlessness thoroughly affects family

and social relationships in modern societies.

Following kin selection theory, Essock-Vitale and McGuire (1985)

analyzed helping behaviour. They found that childless women were

more likely than mothers to give help to their nieces and nephews.2 Yet,

it was also found that childless women were more likely than mothers to

receive help from their nieces/nephews. They suggested that childless

individuals could act as ‘helpers at the nest’.

In our research, we investigated whether childlessness affects financial

help between siblings in a modern society. Childlessness is predicted to

influence the financial relationships between siblings, even while

controlling for social and other aspects of the sibling relationship.

Methods The first data wave of the Netherlands Kinship Panel Study dataset

was obtained through the Netherlands Interdisciplinary Demographic

Institute (NIDI). The sampling procedure, survey questions and

variables are extensively described by Dykstra and colleagues (2004).3

Forty years is assumed to be more or less the age past which

reproduction is not possible, therefore we selected all individuals in the

dataset aged forty or over. Individuals were coded as childless, if they

did not have children by any means (including adoption) and stated they

did not want children in the future, in the case of men. Respondents

were surveyed about their relationship with a randomly selected sibling.

The following variables were selected and/or constructed as predictor

variables for ‘financial help given’ and ‘financial help received’: genetic

relatedness (full versus adopted or half-sibling), childlessness, sibling

childlessness, education level, interest given in the sibling’s personal

life over the past three months (not at all/once or twice/several times),

interest received (same categories), conflict (same categories), financial

balance (I give more/equal/other gives more), initiative of contact

(respondent takes initiative/equal/sibling takes initiative to contact the

other), financial help given/received (have you given/received a

substantial amount of money or valuables to/from sibling over the past

year? If not used as dependent), age, age difference between siblings (in

birth years), sex respondent, sex sibling and number of (full) living

siblings.

Forward stepwise logistic regression was used to investigate which of

the above predictors influences the likelihood of giving (or receiving

from) money/valuables to a sibling.4 Here, we report only the significant

predictor variables, model fits and odds ratios for relevant variables.

Discussion Childlessness affects the likelihood of giving and receiving

‘financial help’ to/from a sibling. This finding is similar to the

results found by Essock-Vitale and McGuire (1985). This

suggests that childlessness is an important factor for helping

behaviour amongst kin in modern societies.

Yet, our study is unable to determine the actual fitness

consequences of these differences between childless individuals

and parents in giving and receiving money or valuables.

Further research is necessary to investigate the effects of

childlessness on financial aspects of kin and social

relationships. Preliminary study of friendship relations shows

that childless individuals are also significantly more likely to

give money or valuables to their friends. Although often

neglected, the trade off between investments in children and

investments in other social and kin relations might be an

important aspect for the study of the evolution of cooperation

and altruism.

Conclusion

Childless individuals are significantly more likely to give a substantial amount of money or valuables. Yet, childless individuals are also more likely receive money or valuables from their sibling.

In modern societies childlessness thoroughly affects the

financial relationships between siblings, even while controlling

for important social characteristics of the relationship. Yet,

further research is necessary to investigate the importance and

the possible fitness consequences of this phenomenon.

References/acknowledgements1. McAllister F. & Clarke L. (1998). Choosing Childlessness, London: Family Policy

Studies Centre.; DeOllos I.Y. & Kapinus C.A. (2002). Aging childless individuals and couples: Suggestions for new directions of research, in Sociological Inquiry, 72: 72-80.; Park K. (2005). Choosing Childlessness: Weber’s Typology of Action and Motives of the Voluntarily Childless, in Sociological Inquiry, 75: 372-402.

2. Essock-Vitale S.M. & McGuire M.T. (1985). Women’s lives viewed from an evolutionary perspective. II. Patterns of helping, in Ethology and Sociobiology, 6: 155-173.

3. Dykstra P.A., Kalmijn M., Knijn T.C.M., Komter A. E., Liefbroer A.C. & Mulder C.H. (2004). Codebook of the Netherlands Kinship Panel Study, a multi-actor, multi-method panel study on solidarity in family relationships, Wave 1. NKPS Working Paper No. 1, The Hague: Netherlands Interdisciplinary Demographic Institute.

4. Pampel F. C. (2000). Logistic regression: A primer, Quantitative Applications in the Social Sciences Series #132, Thousand Oaks: Sage Publications.

Acknowledgements: I would like to thank NIDI for access to the data and the members of the evolutionary psychology research group at the University of Liverpool, as well as the other Msc. Students, for their comments. The research presented here is part of my MSc. thesis at the University of Liverpool.

‘The Netherlands Kinship Panel Study is funded by grant 480-10-009 from the Major Investments Fund of the Netherlands Organization for Scientific Research (NWO), and by the Netherlands Interdisciplinary Demographic Institute (NIDI), Utrecht University, the University of Amsterdam and Tilburg University’

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