| Title |
Fraternal Birth Order, Family Size, and Male Homosexuality: Meta-Analysis of Studies Spanning 25 Years
|
|---|---|
| Published in |
Archives of Sexual Behavior, June 2017
|
| DOI | 10.1007/s10508-017-1007-4 |
| Pubmed ID | |
| Authors |
Ray Blanchard |
| Abstract |
The fraternal birth order effect is the tendency for older brothers to increase the odds of homosexuality in later-born males. This study compared the strength of the effect in subjects from small versus large families and in homosexual subjects with masculine versus feminine gender identities. Meta-analyses were conducted on 30 homosexual and 30 heterosexual groups from 26 studies, totaling 7140 homosexual and 12,837 heterosexual males. The magnitude of the fraternal birth order effect was measured with a novel variable, the Older Brothers Odds Ratio, computed as (homosexuals' older brothers ÷ homosexuals' other siblings) ÷ (heterosexuals' older brothers ÷ heterosexuals' other siblings), where other siblings = older sisters + younger brothers + younger sisters. An Older Brothers Odds Ratio of 1.00 represents no effect of sexual orientation; values over 1.00 are positive evidence for the fraternal birth order effect. Evidence for the reliability of the effect was consistent. The Older Brothers Odds Ratio was significantly >1.00 in 20 instances, >1.00 although not significantly in nine instances, and nonsignificantly <1.00 in 1 instance. The pooled Older Brothers Odds Ratio for all samples was 1.47, p < .00001. Subgroups analyses showed that the magnitude of the effect was significantly greater in the 12 feminine or transgender homosexual groups than in the other 18 homosexual groups. There was no evidence that the magnitude of the effect differs according to family size. |
X Demographics
The data shown below were collected from the profiles of 242 X users who shared this research output. Click here to find out more about how the information was compiled.
Geographical breakdown
| Country | Count | As % |
|---|---|---|
| United States | 42 | 17% |
| United Kingdom | 12 | 5% |
| Canada | 10 | 4% |
| Spain | 8 | 3% |
| Argentina | 5 | 2% |
| Mexico | 3 | 1% |
| Venezuela, Bolivarian Republic of | 3 | 1% |
| Australia | 3 | 1% |
| South Africa | 3 | 1% |
| Other | 21 | 9% |
| Unknown | 132 | 55% |
Demographic breakdown
| Type | Count | As % |
|---|---|---|
| Members of the public | 198 | 82% |
| Scientists | 28 | 12% |
| Practitioners (doctors, other healthcare professionals) | 10 | 4% |
| Science communicators (journalists, bloggers, editors) | 3 | 1% |
| Unknown | 3 | 1% |
Mendeley readers
The data shown below were compiled from readership statistics for 122 Mendeley readers of this research output. Click here to see the associated Mendeley record.
Geographical breakdown
| Country | Count | As % |
|---|---|---|
| Unknown | 122 | 100% |
Demographic breakdown
| Readers by professional status | Count | As % |
|---|---|---|
| Student > Bachelor | 17 | 14% |
| Student > Master | 15 | 12% |
| Student > Ph. D. Student | 13 | 11% |
| Researcher | 10 | 8% |
| Student > Doctoral Student | 8 | 7% |
| Other | 23 | 19% |
| Unknown | 36 | 30% |
| Readers by discipline | Count | As % |
|---|---|---|
| Psychology | 33 | 27% |
| Medicine and Dentistry | 15 | 12% |
| Agricultural and Biological Sciences | 9 | 7% |
| Social Sciences | 8 | 7% |
| Neuroscience | 5 | 4% |
| Other | 14 | 11% |
| Unknown | 38 | 31% |
Attention Score in Context
This research output has an Altmetric Attention Score of 273. This is our high-level measure of the quality and quantity of online attention that it has received. This Attention Score, as well as the ranking and number of research outputs shown below, was calculated when the research output was last mentioned on 13 February 2024.
All research outputs
#134,654
of 25,866,425 outputs
Outputs from Archives of Sexual Behavior
#90
of 3,794 outputs
Outputs of similar age
#2,830
of 335,920 outputs
Outputs of similar age from Archives of Sexual Behavior
#1
of 49 outputs
Altmetric has tracked 25,866,425 research outputs across all sources so far. Compared to these this one has done particularly well and is in the 99th percentile: it's in the top 5% of all research outputs ever tracked by Altmetric.
So far Altmetric has tracked 3,794 research outputs from this source. They typically receive a lot more attention than average, with a mean Attention Score of 33.6. This one has done particularly well, scoring higher than 97% of its peers.
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We're also able to compare this research output to 49 others from the same source and published within six weeks on either side of this one. This one has done particularly well, scoring higher than 97% of its contemporaries.