Srila Prabhupada explained that if a person accepts a donation, he becomes indebted to the person who gives the donation and as a result he may have to accept that person as his son or daughter in a future life to pay back the debt of that person giving money if he uses that money for his own sense gratification.
Therefore the profession of begging is considered to be very risky in terms of karma.
But a Krishna conscious devotee doesn’t use the money for sense gratification, gives it to the service of Guru and Krishna. So whatever karma, whatever is absorbed that person becomes rather, Krishna becomes indebted to him in that sense.
So that person gets rewarded by opportunities to serve Krishna more and more and to ultimately achieve complete liberation, you see. Of course if the devotee doesn’t complete the cycle then of course he may have an unusual son in the future. It’s hard to say but this is the karma involved.HH Jayapataka Swami Lecture – Srimad Bhagavatam 8.19.41 December 17th, 1982