Many years ago I have seen an issur (i don’t remember where) of brothers and sisters touching. We know that most poskim say it is assur for brothers and sisters to be meyached. However, I see many people don’t keep to that. so my question is, may a brother and sister touch, and if yes, may they kiss each other.

If touching does not cause any hormonal reaction then one can allow brothers and sisters to touch. They probably should not kiss. Rabbi Zalman Melamed