Professor Young’s experiments with prairie voles revealed what poets never could: how the brain processes that fluttering feeling in the heart.

The change followed a sweeping review by England’s National Health Service that found “remarkably weak” evidence for youth gender treatments.

© Iain Masterton/Alamy Live News

Five European countries have recently restricted hormone treatments for adolescents with gender distress. They have not banned the care, unlike many U.S. states.

© Tori Ferenc for The New York Times