Blending Kids By Birth and Adoption

When most people think of the label “adoptive family,” they usually think of families where all the children are adopted. The fact is, however, many families in the U.S. are made up of kids blended together in the home by both birth and adoption.
The National Survey of Family Growth found that “an equal percentages of women who have and who have not had a birth have adopted children” and that “four times as many men who have fathered children have adopted children compared with women who have given birth.” 1 While the language is a bit convoluted, suffice it to say, that’s a lot of families that are blended by birth and adoption.

Reasons for Blended Families of Adopted and Non-Adopted Kids

It’s not easily discernible why families are choosing to have both adopted and biological kids. Certainly, reasons such as unexplained secondary infertility, wanting to have children in a second marriage at an older age, and the desire to adopt even though they have not experienced infertility are very common. It’s also apparent that more families are going back into fertility treatment after adopting, and while many of them have questions about a how to do that well, many of them are also successful 2.

Do Parents Favor Their Bio Kids Over Adopted Kids

One big concern prospective parents have as they prepare for an adoption is “will we be able to love our adopted children as we do our biological children?” It’s a common concern and one that has been researched extensively. Scientists have speculated that evolution would logically predict that parents would favor their biologically related children over their adopted kids. This theory, known as the Kin Selection Theory, further predicts that parents should also have less favorable perceptions of the intellect, personality and other behavioral traits of their adopted kids, compared with their biological children.

Research sheds light on this evolution theory of how parents of both adopted and non-adopted kids view their children. Researchers studied 135 virtual twin pairs—similar aged unrelated siblings raised together. Of the virtual twin pairs, 41 were adopted/biological pairs and 94 were adopted/adopted pairs. The average age of the children in this study was 6 years 3.


The children’s IQ was tested and the parents were asked to fill out an Adjective Checklist and a Child Behavior Checklist for both children in the virtual twin pairs.

Biological children scored higher on IQ tests than did adopted children, which is consistent with prior research.

In general, the study found that that parents did not favor their biological children over their adopted children. “Although parents rated their adoptive children higher in negative traits and behaviors like arrogance and stealing, they scored both adopted and biological children similarly when it came to positive traits like conscientiousness and persistence.” 4 Keep in mind that the number of adopted/biological virtual twin pairs was small and the children studied were young, but the findings are still interesting and likely reassuring if you are parenting a blended family.

That’s Good News, But Now What?

While it is very common for parents to worry over issues of favoritism in blended families, it’s important to know that there are tools to help you navigate those issues well. When parenting kids in a blended family, parents need to think through the special issues that can arise. Both biological and adopted children can thrive in a blended family, but it certainly helps for adoptive parents to be educated and equipped.

This tip sheet, Top Ten Tips for Blending Children by Birth and Adoption 5 from our partners at Creating a Family is a good starting point for parenting in the trenches of virtual twinning or blended families. We
also suggest 8 Ways to Engage with Your Child & Encourage Family Communication 6 by C.A.S.E. as a tool for building strong connections between you and your children and your children with each other.

1 Who Adopts? Characteristics of Women and Men Who Have Adopted Children:

3 Do parents favor their adoptive or biological children:

4 Do parents favor their biological children over their adopted ones:

6 8 Ways to Engage with Your Child & Encourage Family Communication: