Are harry potter and lord voldemort relatives?

According to this family tree, they are DISTANT relatives. In the source you will see that the line is broken, this suggesting that the Gaunt family married into the Peverell family. Harry and Voldermort are not blood relatives but relatives by marriage. The same theory applies to Harry and Ron. Harry married Ginny, so some may consider Ron to be his relative. Ron is related to Harry through family ties, not blood.