Parents should tell children if born via surrogacy or egg or sperm donation
The study says children should know before they reach 7 years old
Children born via surrogacy or egg or sperm donation should be told of their biological origins before they start school.
The study by the University of Cambridge said there was "no difference" in psychological wellbeing or quality of family relationships between children born by these types of assisted reproduction and those born naturally by the time they reach the age of 20.
Academics from the University of Cambridge tracked a number of families from infancy to early adulthood.
The team examined survey and interview responses from 65 assisted reproduction families, including 22 surrogacy families, 17 egg donation families and 26 sperm donation families, and compared them with responses from 52 families who conceived naturally.
Researchers found young adults who learned about their biological origins before their seventh birthday had less negative relationships with their mothers.
Their mothers also showed lower levels of anxiety and depression.
Study lead author, Professor Susan Golombok, said: "Despite people's concerns, families with children born through third-party assisted reproduction - whether that be an egg donor, sperm donor or a surrogate - are doing well right up to adulthood."
"There does seem to be a positive effect of being open with children when they're young - before they go to school - about their conception."
She added: "Today there are so many more families created by assisted reproduction that it just seems quite ordinary.
"Really wanting children seems to trump everything - that's what really matters"
"But 20 years ago, when we started this study, attitudes were very different - it was thought that having a genetic link was very important and without one relationships wouldn't work well.
"What this research means is that having children in different or new ways doesn't actually interfere with how families function.
"Really wanting children seems to trump everything - that's what really matters."