By this statement I intend to stress the fact that atoms are not dispersed in a random distribution in a general mixture with the myriad of other atomic species which constitute matter. We find gold where there is gold, just as in the Wild West of America one found wild horses where there were other wild horses. The 'herding instinct' is at work in the latter case but, more to the point, there is the 'creation and survival factor'. People are 'created' where there are people and it does not need a physicist to tell you why. There are two principal factors which govern this circumstance, the emergence of the embryonic form and its survival after birth.
Survival depends upon community, collective association and parental care.
In the particle world of the physicist the close association of two particles of opposite electrical polarity, a parent particle and a 'seeding' particle, given energy input, can create a parent and offspring, which separate to build a family of mixed polarity but like particle forms. That is something you can read about elsewhere in these Web pages. However, following the creation of such particles, they are subject to processes of decay much as applies to us humans. They have interplay of energy amongst themselves and the rest of the particle world. They are bombarded at random by energy activity from the background environment, but their chance of survival is enhanced by a mutual proximity which allows them to nurture one another by pooling their energy.