In SN 35.145 (below), we see that the body, intellect etc. is "old karma", capable to be felt. But it doesn't say whose "old karma" it is. The sutta also talks about "new karma" generated by decisions and actions within our control, but also not pinned to a specific individual self identity. Also SN 12.37 reiterates this.
"Now what, monks, is old kamma? The eye is to be seen as old kamma, fabricated & willed, capable of being felt. The ear... The nose... The tongue... The body... The intellect is to be seen as old kamma, fabricated & willed, capable of being felt. This is called old kamma.
The following comes from SN 12.17 (although this quote comes from here). Here, karma is not pinned to a specific self identity or a specific individual. Karma is attributed to past decisions and actions, coming from dependently originated conditions.
Again, when the Buddha was asked by the naked ascetic Kassapa whether suffering was of one's own making or of another's or both or neither, the Buddha replied "Do not put it like that." When asked whether there was no suffering or whether the Buddha neither knew nor saw it, the Buddha replied that there was, and that he both knew and saw it. He then said "Kassapa, if one asserts that 'He who makes (it) feels (it): being one existent from the beginning, his suffering is of his own making,' then one arrives at eternalism. But if one asserts that one makes (it), another feels (it); being one existent crushed out by feeling, his suffering is of another's making,' then one arrives at annihilationism. Instead of resorting to either extreme a Tathaagata teaches the Dhamma by the middle way (by dependent origination)".
From MN 38, SN 22.85, SN 12.20 and other suttas, and from "sabbe dhamma anatta" (all phenomena is not self - Dhp 279), we have learned that there is no specific individual self that is permanent, unchanging and continues to wander within this or other lives. The endeavouring being (self) (AN 6.38) is ever-changing and arises from dependently originated conditions.
So, where does the "old karma" which generated our physical body and our mind come from?
Does it come from our parents, family, community, media, books, surroundings?
Are there any scriptural references or commentaries to support this?