image credit: pinterest.com Women who shared their mother's womb with a male twin are less likely to graduate from high school or college, have earned less by their early 30s, and have lower fertility and marriage rates when compared with twins who are both female, according to new Northwestern University research. In the largest and most rigorous study of its kind, Northwestern University and Norwegian School of Economics researchers examined data on all twin births in Norway over a 12-year period to find that females exposed in utero to a male twin experienced adverse educational and labor outcomes along with altered patterns of marriage and fertility as adults. "Nobody has been able to study how male twins impact their twin sisters at such a large scale," said study corresponding author Krzysztof Karbownik, an economist and research associate at Northwestern University's Institute for Policy Research (IPR). "This is the first study to track people for mo...