Prior to 1970, it was rare that parents disputed custody

parental alienation

I speak of psychiatrist Richard Gardner's Parental AlienationSyndrome (1987.)
..... Prior to 1970, it was rare that parents disputed custody of their children. .....
that usually both parents will get into an alienatiing cycle that must be stopped. ...

http://parental-alienation.tripod.com/id11.html