Sehe ich ganz anders.

> Wie wahrscheinlich ist es denn, dass der Stiefvater seine Stiefkinder misshandelt? Da hätte ich jetzt doch mal eine Quelle.

Misshandlung und Missbrauch sind die Ausnahme, nicht die Regel, auch bei Stiefkindern. Aber die Wahrscheinlichkeit für beides steigt statistisch auf ein Vielfaches, wenn die Mutter eine neue Beziehung eingeht.

https://www.ojp.gov/ncjrs/virtual-library/abstracts/prevalence-and-seriousness-incestuous-abuse-stepfathers-vs

https://en.wikipedia.org/wiki/Cinderella_effect

" "In 1973, forensic psychiatrist P. D. Scott summarized information on a sample of "fatal battered-baby cases" perpetrated in anger ... 15 of the 29 killers – 52% – were stepfathers."[1] Although initially there was no analysis of this raw data, empirical evidence has since been collected on what is now called the Cinderella effect through official records, reports, and census.

For over 30 years, data has been collected regarding the validity of the Cinderella effect, with a wealth of evidence indicating a direct relationship between step-relationships and abuse. This evidence of child abuse and homicide comes from a variety of sources including official reports of child abuse, clinical data, victim reports, and official homicide data.[2] Studies have concluded that "stepchildren in Canada, Great Britain, and the United States indeed incur greatly elevated risk of child maltreatment of various sorts, especially lethal beatings"
...
In addition to displaying higher rates of negative behaviors (e.g., abuse) toward stepchildren, stepparents display fewer positive behaviors toward stepchildren than do the genetic parents. For example, on average, stepparents invest less in education, play with stepchildren less, take stepchildren to the doctor less, etc
...
Children are not only vulnerable to abuse by their parents, but they are also dependent on their parents for supervision and protection from a variety of other harms.
...
Based on data gathered from the Australia National Coroners' Information System, stepchildren under five years of age are two to fifteen times more likely to experience an unintentional fatal injury, especially drowning, than genetic children. "

Interessant ist die evolutionspsychologische Deutung :

"Unlike the lion, however, humans in a stepparenting situation face a more complicated tradeoff since they cannot completely disown their partner's offspring from a previous relationship, as they would risk losing sexual access to their partner and any chance of producing potential offspring.... This mating effort hypothesis suggests that humans will tend to invest more in their genetic offspring and invest just enough in their stepchildren."