History require physical answers based on facts or one can say, historical details. The same would apply here except that no supernatural powers are to be used, and secondly, in fair manner, the physical reasons must satisfy ALL QUERIES that can come in an average mind.
YADUS(YADAVS) were at that stage proficient in Genetic engineering and Human Cloning. Transplant of embryo of Lord Balram and Lord Krishna was done much earlier. The entire tribe was GAINFULLY employed and DECENTLY earning because of this.