Internodes Spacing

Ok ive got a few questions about internode spacing.
I know that indicas are supposed to be bushy(tighter spacing) and sativa taller….
Ive also heard that using mh lighting for veg makes a bushier plant while hps makes them stretch more….BUT

Which has more of an impact on node spacing, genetics(ie. Indica vs. sativa) or light type(ie. MH vs. HPS)???

Basically im just wondering if my HPS light is going to make my K2(indica) stretch???

Also, I was wondering if topping or fimming have an impact on node spacing??? Or do they just bush out the plant?
I know that it makes them grow multiple tops but I have no idea about its effect on node spacing.

Thanks in advance for any responses.
Preferably someone with experience of growing an indica strain with an HPS light.

There wont be as much of a difference between MH and HPS as there will be with a pure sativa and a pure indica, now if you were using incandescent lights or had your cfls too far away then the light would make them strech more than genetics.

I don't know for sure but I don't think that topping will have an affect on node spacing.