Arranged marriages among micro communities can be infact termed as lighter version of Incest ( Marrying one's brother/sister/cousin ) .
Genetics ain't simple , a healthy looking person may not pass on healthy genes ( recessive traits are passed in stealth ) .
Micro communities in this modern age, where people prefer , to have a single child , shall reach elimination . Earlier this was not the case as , say amongst 5 Kids , even if 2 would'nt reach adulthood , the rest 3 could continue the progeny .
Also in society at large , arranged marriages perpetuate the tendency of human souls identifying themselves as belonging to a certain caste as both the partners belong to the same caste . And thus spiritually speaking is regressive .
The greatest dent to the spiritual progress of a human is identifying oneself with labels and especially labels which denote a sense of superiority or inferiority . There cannot be a worser label than caste .
Our minds have to thus welcome every human soul for what they are and not because they come with a superficial TAG .
Papa isn't going to study genetics but WE SHALL.