What is the tender-Years theory regarding custody?

Answer 1

its saying that the child should stay with the mother during the tender years which is up until about 12. yet most states don't really look at it because its absolute garbage. A) tender years arent up to 12. and B) if a mother isn't a fit mother then the "tender years" should be with the father. So it exists, yet most courts don't use it as reason for custody