But 8.6% of those who had at least one biological parent who abused drugs had their own abuse problems versus 4.2% of adoptees whose biological parents did not have a history of drug abuse.

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Many parents who chose not to tell were concerned, she said, that they would be able to give relatively little information about the biological parent - as sperm donation is carried out on an anonymous basis.

BBC: Donor sperm children 'kept in dark'

Ms MacCallum said the fact parental warmth and quality of parenting was similar in all three groups showed "it is the level of commitment to parenting that is important, and not the presence or absence of biological links between parent and children".

BBC: NEWS | Health | Donor embryo children 'not told'

While more of these families might have access to health insurance after the implementation of the Affordable Care Act, right now, among same-sex couples raising biological, adopted or stepchildren, at least one parent or child does not have health insurance in 38% of same-sex couple families.

CNN: The real 'modern family' in America