This is regarding caste of the children born in intercaste marriages. Hinduism recognises two types of intercaste marriages. In one case yhe husband belongs to higher caste and wife to a lower caste. It is called an anuloma marriage. If the husband belongs to a lower caste and wife to a higher caste then it is called pratiloma marriage.
In anuloma marriage the children belong to the caste of the mother. In pratiloma marriage the children belong to a caste even lower than the husbands caste. Devayani, daughter of Shukracharya was a Brahmin girl. She wanted to marry Yayati, a king and hence a kshatriya. First Yayati refused but later married her fearing the curse of her father. Their son was Yadu. Yadu's descendants are Yadavas. As Yadavas including Lord Krishna came out of pratiloma marriage they got the status of OBC,s and reservations.
As Yayati was a kshatriya also a high caste, though lower than Brahmins, Yadavas are not that low in caste.The children will belong to proportionally lower caste with the increase in caste difference in pratiloma marriages. Sometimes the children will belong to comparatively higher Scheduled castes. Those who want to know more may read "Stories for the Innocent" by Rajaji.