“Half as likely” means that there are some non-biological children (what, are they robots?) who are caring for their step-parent or adoptive parent. The observations of the study are intuitively obvious, but they’re generalizations, not descriptive of every case.
I hear ya. What about kids who don’t know who their parents are?
Studies and polls are amusing sometimes, but I take it with skepticism, like my horoscope...
I’m sure my sister and brother (OK, half-) would help my/”our” father.
When 6, they asked him on getting married if they could call him “Daddy”.