The subject keeps coming up – Heiko Otto’s partner usually broaches it – and with increasing frequency now after the birth of their third child. The subject is a vasectomy, the medical term for male sterilization. “All the other methods of contraception have a drawback, and female sterilization involves more extensive surgery,” Otto says. “It’s often the woman who takes responsibility for birth control, which isn’t quite fair. My partner would like me to have the procedure.” But Otto, 41, is undecided. He says he’s still in “the discovery phase.” “It stirs something up in me,” he explains. “No…