So... I am going to be posting some unpopular opinions regarding this "issue", which is the fact that I rather enjoy the idea of Heritage Ancestry feats. HOWEVER - It seems that Paizo has thrown the "Heritage" keyword on many Ancestry feats that don't deserve the tag.
To me - a Heritage feat should be something that represents a different genetic heritage and/or an intervention from another species or influence. For example, the Dwarf's "Ancient's Blood" feat is a perfect example of what (I feel) would be considered an accurate Heritage feat - as it specifically points out that you're resistant due to your Heritage rather than directly due to your Ancestry.
At the same time, the Hardy trait seems more like an Ancestry thing and less of a Heritage thing. I don't believe sickly, or anything less than "hardy" is something used to describe a Dwarf, so why are we restricting it to only a few Dwarfs with specific breeding that might cause this phenomenon to occur?
Another example of this poor Ancestry vs Heritage trait can be seen in the Elf's Keen Hearing feat (I guess that means Half-Elves can't have Keen hearing like their elvish ma or pa).
Even more argumentative is that the Goblin's Flame Heart feat SPECIFICALLY calls out that this happened during Childhood and not because you were born with the specific genes required to trigger this mutation.
My 2 cents: Save the Heritage feats for sub-species of the Race (i.e.: Drow or Aquatic Elves for the Elf race), instead of key features that should be shared between all of the available creatures in that race.