As far as culture goes, it really depends on the individual's personality as well as how they were raised. When it comes to social purposes (identity, navigation, labels, representation, etc) though, too much mixing will result in 1)the diluting of unique phenotypes and, eventually in 2)the replacement of the original demographic. There is a reason that mixing has remained so taboo throughout multiple generations; it originates from self-preservation[via the collective] and the need to maintain culture via bloodlines(since humans are 'tribal' creatures, we feel an affinity for those who resemble us[in-group preference]).
Anyways, it's not the end of the world if a few individuals mix here and there BUT pure lineages should be careful not to label them as 100% "_____" or else the community will suffer the same consequences that the AA community are currently dealing with (due to the after-math of that racist 'one drop rule'). I'm not saying to exclude or reject mixed members of the community or anything like that, obviously it's okay to embrace them and have them participate as long as they acknowledge that they aren't full/pure. I just propose to call them 'mixed Somali' (for example*) rather than just 'Somali' ..and this is regardless of whether it is the father or mother who is 'other'/ajnabi, cuz IMO...mixed is mixed, genetically it results in the same thing. Somalis should be glad to have a fairly homogeneous ethnicity rather than naively allowing further divisions to fester (the alternative will only succeed in creating confusion, hierarchies, colorism, loss of bond/identity, etc.) Just my [long-winded] 2 cents.