No. I am an adoptee, and have found siblings, half-nieces and nephews, first cousins, and first cousins once removed, etc. on both maternal and paternal sides of the family. The woman who gave birth to me had four children. I have found one first cousin once removed on the maternal side whose mother was adopted. The "Removeds" on the maternal side? Their father was adopted. On the paternal side, one of my cousins was adopted.
When you go back that many generations, I think it's even more common to find adoptees. People didn't live as long, and children were placed with relatives or neighbors/good friends. It gets harder to find genealogical relatives when parents died young and children were raised by aunts, grandparents, in-laws, etc. and there were no records kept.