Single parent and their children

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5226056/

https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0062701

https://www.sciencedirect.com/science/article/abs/pii/S0165032718307900?via%3Dihub