Mama's boys and sex

A mother figure's influence on her son's sexual preference is so strong that a billy goat raised by a female sheep prefers ewes to nanny goats. Researchers led by Keith Kendrick at the Babraham Institute in Cambridge replaced lambs with kids soon after birth. Throughout their childhood, the young goats had free access to other goats. As adults, the billy goats preferred sheep for socialising and mating. Nanny goats were less affected by their foster mothers.

From Nature 395, pp229-230.