I just watched a 1946 movie called Shadow of a Woman. The main character is an unscrupulous quack who mistreats everyone and is probably a murderer. He refuses to let his 5-year-old boy eat solid food, and only gives him orange juice. He has a custody fight with his ex-wife, and her lawyer can only think of one winning argument: moral turpitude! The lawyer has evidence that the man spent the night with a woman without benefit of marriage. When a marriage license is produced, the case evaporates. Starvation was apparently not as important as potential immoral influences.
How times have changed. Now, the most flagrant adultery would have no bearing on a custody dispute. Even if my wife is bringing the kids along to her boyfriend's house while she commits adultery, the court ignores it. On the other hand, if I fail to floss the kids' teeth or I let them out of my sight in the grocery store, then I'll be sent to a parenting class or lose custody.