Family Search is a LDS (Mormon) URL, based on actual documents, not DNA. They are building a large family tree data base which they obviously hope some day could be almost universal. You look up your oldest known ancestor, and find his/her parents, etc.
The problem is, not all people are whom they think they are. In other words, for a variety of reasons a person's father may not be the father, but someone else. This needs no explanation in most cases. But, there are rapes during wars centuries ago. And, when unwed pregnancy destroyed the entire family, not just the unwed mother, if a girl got pregnant, her mother would also hide away and when the baby was born present it as her child. And, foundlings were raised as family members, that digressed from any usable DNA record.
A LSD told me that the actual blood record did not matter to them. If you were raised as a family member, that was your family, period. Blood did not matter. If you learn wht LSD folk do with their ancestry, you would understand why they take this viewpoint.