In 16th-century England, the age of consent was set at 10 years old in an effort to protect young girls from sexual abuse by adult men. In 1875, parliament raised the age of consent to 13; in 1885, it upped it to 16. Now, a leading public health advocate has proposed that the United Kingdom bring the age down again in light of the high proportion of British adolescents who are having sex—with one another—before they’re legally capable of granting consent. Lowering the age of consent to 15 (where it stands in Sweden) or 14 (where it’s set in Germany...