It's true. When I worked at a small, old school, conservative (not exactly a Goldman-like pit of debauchery) investment firm in San Francisco 20 years ago, they had a strict unwritten rule against hiring...not women, but young, attractive women. When we saw one come in for an interview, we all knew right away that
she wasn't getting hired. The old man knew exactly what kind of disruption would ensue and wouldn't have it in his company. The firm had no problem hiring older, married women - even into senior positions. But the 30-ish management staff was nearly all male.
When a large company bought us out a couple of years later, the rule had to go away. But there was no way to test the old man's thesis, as the firm began an immediate transformation into the typical, HR-ruled corporate theocracy.