Tieflings are descendants from evil(subtype) outsiders. This connection is usually not direct but more so generational. A Tiefling and non Tiefling having a child have a high chance of producing another Tiefling. That chance is almost guaranteed if the mother is a Tiefling. And unlike most outsider offspring's they don't have an extended lifespan and even tend to live a little bit shorter than humans.
Generally Tieflings are seen in a relatively positive light. Whilst there ancestors might be evil in nature they do have power above that of normal humans and are respected for it. The exception to this are Tieflings who have visible scurs.
Scurs
A Tieflings evil origins can catch up to them. If a Tiefling performs deeds in accordance with there heritage it can have a lasting example on them. The most common is for there horns to grow larger and for horns to start appearing randomly on there body. These deformaties are called scurs. This is unrelated to how the Tiefling feels about these deeds. If the act according to the nature of there ancestor scurs will appear. And if they refrain from this behavior the scurs will slowly go away. If a Tiefling keeps acting according to the nature of there ancestor more and more scurs will appear and eventually there body will start morphing to look less humanoid. When these scurs get really severe the Tiefling will start to act more and more aggressive until eventually they morph into a monster overnight and lose all reason.
As an example if a Tiefling with Kyton heritage starts torturing people or mutilating himself he'll start growing chains on his body.
A small Scur will usually goes unnoticed since Tieflings have horns and sometimes even scales from birth. But once a lot of scurs start growing on a person there usually outcast. After all a Scur is basically an admission to doing something cruel.
Adendum, Hungerseed.
The Oni are known for there hedonism and excess. This mostly comes in the forms of Gluttony, Lust, and Masocism trough combat. Scurring in hungerseed most often happens as a result of overindulgence in lust or food, either by quantity or quality. Beyond this the hungerseed of lesser oni also develep scurs as a result of excessive and brutal combat tho this is quite uncommon. Excesive drinking does not on its own lead to scurring but whilst drunk one often performes other behaviours that cause scurring.
Mashida and
Uchimura both use there quasi divine powers to controll there liniage. Both of them crave the death of others for there own reason making there spawn not scurr from combat.
Mashida supports his clan and allows his spawn to be more rowdy and enjoy raucus. He protects them with scurring making them scurr far less easily. In adition blood helps temper scurring and Mashida himself can perform a ritual where he removes scurs from his disciples. However touching Mashida's food by consuming verry high quality food or enganing in canibalism will cause scurs verry quickly. He also shares some his battle prowes with his clan so they may fight for him. (Automaticly get the oni weapon familiarty feat only relating to the Tetsubo)
Uchimura is resentfull of her faith and wishes the whole world to share her suffering. To this end spawn of Uchimura tends to slightly worsen the quilty of food they touch over time and scur much more easily form eating quality food. To this end most of her followers only eat verry stale rations or tastless food created with magic. Some even swear of food all together with the aid of magic. In exchange for this they gain some of the midnight queen's resitance, as well as some of her battle prowes to do her bidding. (Automaticly get the oni weapon familiarty feat only relating to the Khakkara and a +1 status bonus against poison effects). Whilst they do not scurr from consuming alcohol there constitution often makes them unable to enjoy the "buzz" it gives. The taste can still be enjoyed however.
Mechanics (no 1e sadge)
Tieflings maximum age is 70+1d20 years not +2d20.
Your allowed to take variant Tiefling heritages and are encouraged to do so. Your allowed to roll the d100 table if you replace your spell like ability. You get one roll no takesie backsie. If you take the fiendish heritage feat you instead roll trice and pick a result. Alternatively instead of rolling on the d100 table you can keep your spell like ability and choice one of the d100 abilities to gain for flavour. In this case the ability can't grant a numerical or potent bonus, your allowed to gain nourishment from ash but your not allowed to gain a +2 to your wis score or all-round vision.
