Hatemi: Not by twins alone: Using the extended family... - Google Scholar
https://scholar.google.com/scholar?cites=10005905925752745289&as_sdt=2005&sciodt=0,5&hl=en
https://scholar.google.com/scholar?cites=10005905925752745289&as_sdt=2005&sciodt=0,5&hl=en