There is no evidence that lesbians’ children are hurt or damaged by meeting their sperm donor fathers, a small study says.

The study, by researchers at the University of Amsterdam in the Netherlands, used data from the US National Longitudinal Lesbian Family Study.

Seventy-eight teenagers were studied, Reuters reports.

A third of the donors knew their offspring, just over a third were permanently anonymous and 18 could be contacted once the child turned 18.

Using questionnaires and interviews, the researchers found no difference in the mental health of teenagers who knew their fathers or did not.

Another study, by the University of Cambridge, interviewed 23 sperm and egg donors who all said they had positive experiences with meeting their offspring and most saw them regularly.

Both pieces of research were published in the journal Human Reproduction.