First-born children more likely to learn about sex from parents

Men report lower parental involvement in sex education than women
Birth order and sex education infographic. Credit: LSHTM

Birth order may play a significant role in how children learn about sex, especially for boys, according to a new study published in the journal Sex Education.

Researchers found that first-born children were more likely to report parental involvement in sex education than later-born children, a pattern which was especially pronounced in men.

Led by the London School of Hygiene & Tropical Medicine (LSHTM), the study is the first to look at the relationship between birth order and two key sexual health outcomes: parental involvement in sex education and early sexual experience.

The study’s authors say that a better understanding of parental involvement in learning about sex could help to inform the design and delivery of sex education programmes.  

Researchers used data from the third National Survey of Sexual Attitudes and Lifestyles (Natsal-3), one of the largest scientific studies of sexual health and lifestyles in Britain. Conducted by LSHTM, University College London and NatCen Social Research, the studies have been carried out every 10 years since 1990, and have involved interviews with more than 45,000 people to date.

Taking a sub-sample of Natsal-3 participants – 5,000 individuals aged 17 to 29 who were either first-born, middle-born or last-born – the team analysed responses to questions about the involvement of parents and siblings in sex education and explored associations with early sexual experiences.

They found 48% of first-born women and 37% of first-born men reported learning about sex from a parent, compared to 40% of middle-born women and 29% of middle-born men.

After adjusting for socio-demographic factors, last-born women and men were significantly less likely than those first-born to report a parent as their main source of sex education. Among men, those middle-born and last-born were less likely than first-born to report having found it easy to discuss sex with their parents when growing up.  Later-born men were also less likely to report learning about sex from their mothers.  

Although there were differences by birth order in parental involvement in sex education, there did not appear to be an association between birth order and early sexual experiences, although middle-born men were at increased odds of being under 16 when they first had sex.

Dr Lotte Elton, who led the research as part of her MSc project at LSHTM, said: “Although there has been much research into how the order in which children are born into a family may impact psychological or social outcomes, studies on the relationship between birth order and sexual health outcomes are limited.

“In addition to seeing differences according to birth order, we also found clear differences between the sexes; across all birth order categories, men consistently reported lower parental involvement in sex education than women. We have seen from previous research that parents are less likely to speak about sexual matters with their male children. Our findings suggest that there may be even less communication about sex with male children if they are middle- or last-born.”

The research also confirmed that, as might be expected, later-born children were more likely to report learning about sex from siblings compared with first-born children, suggesting that education programmes could better equip adolescents on how to do so, particularly where parental involvement in sex education is low.

Wendy Macdowall, senior investigator from LSHTM, said: “Our findings support previous work demonstrating the silence around sex between many parents and their children, particularly their sons, and highlight that the challenges parents face in talking about sex may increase with family size.

“The implementation of statutory Relationships and Sex Education (RSE) in schools from September 2020 will, hopefully, eliminate the current RSE lottery so that all young people can expect good quality sex education. But that doesn’t let us parents off the hook. Young people tell us they want information from school and parents; schools need the support of parents and issues raised at school can be a useful starting point for discussions at home. It is important that we find ways that schools and parents can work together.” 

The authors acknowledge the limitations of the study. Of particular importance is that middle-born children had different socio-demographic characteristics, including social class and ethnicity, compared to first- and last-born children, which means that even with statistical adjustment, the results for middle-born children may reflect socio-demographic differences rather than birth order.

Furthermore, although adjustment was made for sibling number, other sibling factors which were not adjusted for, such as gender and age difference, may have been relevant.

Natsal-3 is one of the largest and most comprehensive studies of sexual behaviour and lifestyles in the world, and is a major source of data informing sexual and reproductive health policy in Britain. Natsal was funded by the Medical Research Council and the Wellcome Trust, with additional funding from the UK Research and Innovation and Department of Health and Social Care.


Lotte Elton, Melissa Palmera and Wendy Macdowall. Birth order and parental and sibling involvement in sex education. A nationally-representative analysis. Sex Education. DOI: 10.1080/14681811.2018.1509305