Abstract
Several hypotheses were stated, why should sibship contellations of partners determine the relationship itself. We tested for assortative pairing, dyadic adjustment and sexual compatibility.
In our study we considered only pairs, where both partners came from the set of two siblings. This cunning experiment design allowed us to include sex and birth order of participant, his/her partner, participants sibling and partners sibling and treat each possible constellation separately without confusing generalizations and simplifications.
Our results suggests that in this case sibship constellations of partners has either none or very small effect on the relationship. Some resarchers also point out , that most visible differences are between firstborns and middleborns.
Two member sibshibs lack the middle child, so the differences between siblings can be stired.