There are several explanations that could serve as hypothesis:<p>- it&#x27;s inherited genetically<p>- it&#x27;s something both their parents transmitted culturally&#x2F;behaviorally because they themselves converged by living together<p>- when you search for similarities between two given individuals you always find some and discard the dissimilarities (it&#x27;s also a mentalist trick<p>Each hypothesis seems hard to test&#x2F;falsify especially with such small samples