Foster Care

Foster care is a system where a child is placed into the care of someone other than their birth parents and family.

History
Martha and her husband took in a young girl named Jubilation Lee. However, they found out she was a mutant and the husband signed her up with Mutant Registration. Jubilee was kidnapped by Sentinels and rescued by the X-Men. She then went to stay at the Xavier Mansion to join the X-Men and learn to use her powers.

Background
While not explained on the series, in the foster care system the child is the legal ward of the state while the foster parents merely handle the day-to-day care of the child. It is possible for foster parents to formally adopt the child.