turkic is wide cathegory, many central asians are R1a.
usually when they consider and expansion of farmers people tend to think a heterogenous accompanionship of certain mithocondrial haplogroups. however in most cases this seems to be non-mandatory. the fast megalithization of europe is a good example, perhaps. why would farmers leave their ancestral home? invasion, drought, adventure, plague? obviously in most cases it would be the women and children to suffer most. most farmer movements were probably male dominated.