Yes and no. Infact it was more so hinted that his mom did what she did so he would be different. Infact the build up was that he didnt need his dad's Gene's to be great. Infact it was so bad that because of whole cake sanji fans were literally mad when I told them that sanjis powers from this point on would not be coming from haki but instead his lineage factor kicking in lol
There was a scene where a doctor states that sanji's genes are modified just like that of his siblings, he just didn't exhibit the traits that his siblings have
Why wouldn't he get a haki power up? Lol futur sight is a given at this point
And him getting coc just fits his character imo
Besides his flames are pretty much confirmed to not be a result of his modifications