half of leaf finger is yellow

[biggerbud420]

is this genitics or a light problem
im growing in pro mix moisture control potting mix
using fox farm happy frog all purpose dry amendments
light is a spiderfarmer sf4000
strain in zkittles
temps 67-76 rh 50-60

 

[crossfader]

Given how the rest of the plant appears, I'd lean toward a genetics issue.