Where does “filiol” come from?

filiol (Old French) comes from Latin filiolus, from Latin filius, from Old Latin filios, from Proto-Italic feiljos, from Proto-Indo-European dʰeh₁ylios, from Proto-Indo-European dʰeh₁(y)- — to suckle, nurse.

Ancestry of “filiol”, step by step

Step	Language	Word	Meaning
1	Latin	filiolus	young son
2	Latin	filius	a son; any male descendant; children
3	Old Latin	filios	son; accusative plural of fīlius
4	Proto-Italic	feiljos	son
5	Proto-Indo-European	dʰeh₁ylios	sucker
6	Proto-Indo-European	dʰeh₁(y)-	to suckle, nurse

Every word from Proto-Indo-European dʰeh₁(y)- →Every word from Proto-Indo-European dʰeh₁ylios →Every word from Proto-Italic feiljos →