Selfish Y chromosome may explain why some families mostly have sons

image via New Scientist

March 3, 2026, 5:13 PM

• •A Utah family with mostly male offspring shows a potential 'selfish' Y chromosome.
• •Selfish chromosomes can skew sex ratios by affecting sperm.
• •Researchers analyzed data from the Utah Population Database over seven generations.
• •Further research is planned to analyze sperm samples for skewed ratios.
• •Selfish Y chromosomes may contribute to male infertility.

A study of a Utah family spanning centuries reveals a possible biological explanation for a disproportionate number of male offspring: a selfish Y chromosome. This chromosome may prevent female births, a phenomenon observed across seven generations. Researchers used the Utah Population Database to analyze the family's data, identifying a significant skew in sex ratios. While further genetic analysis is needed, the findings suggest that selfish chromosomes could impact human fertility and offer insights into evolutionary battles within our genes.

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