http://www.nature.com/news/having-sons- ... cy-1.12516
The study, which appears in Biology Letters, builds on previous research published by the same team in the journal Science more than ten years ago, which found that for every son she had, a woman's life would be shortened by an average of 34 weeks. By contrast, daughters actually lengthened their mother's lifespan very slightly (though not statistically significantly). In both studies, the life-shortening effects were experienced only by mothers, not fathers.
