Having male twin reduces woman's fertility

According to a Finnish study, for women who had a twin brother, they were 25% less likely to have children, 15% less likely to marry, than women who had a twin sister. The possible explanation? Due to being exposed to their brother's testosterone for nine months in the womb, the female twins had more masculine attitudes and behaviors that affected their decision to get married, or attractiveness to mates. I am not sure if this founding has anything to do with the ever popularity of The Olsen Sisters.