As a long time gamer, I've noticed that I loved creating my character's past and personality, but typically abandoned what I created anyway as I got to know my character better through play. I wanted to believe in DAS, but ultimately leaned toward DIP.

In the last few years, I've become interested in narrative writing and have learned why this is. In storytelling a character's past, education, appearance, intelligence, mannerisms, etc. (the kind of stuff that exists on a PC's character sheet) is considered characterization not character. True character on the other hand, can only be determined by the choices a character makes particularly when the choices are risky or bear a price. This kind of thing tends to happen in game-play not character creation.

They can take any race-restricted character option

As pointed out in this answer, in Pathfinder, most half-breeds of humans are also treated members of both parent races, and thus, also treated as humans. This rule extends to:

• Half-orcs

Orc Blood: Half-orcs count as both humans and orcs for any effect related to race.

• Half-elves:

Elf Blood: Half-elves count as both elves and humans for any effect related to race.

• Aasimars with Scion of Humanity racial trait:

Scion of Humanity: Some aasimars’ heavenly ancestry is extremely distant. An aasimar with this racial trait counts as an outsider (native) and a humanoid (human) for any effect related to race, including feat prerequisites and spells that affect humanoids.

• Tieflings with Pass for Human racial trait:

Such a tiefling doesn’t need to succeed at a Disguise check to appear to be human and count as humanoid (human) as well as outsider (native) for all purposes (such as humanoid-affecting spells like charm person or enlarge person).

• Sylphs, Undines, Oreads and Ifrits with Mostly Human racial trait:

Such geniekin appear to be human, save perhaps minor features like unusual eye color, and they count as humanoid (human) as well as outsider (native) for all purposes (such as humanoid-affecting spells such as charm person or enlarge person).

• Fetchlings with the Bound to Here racial trait:

Fetchlings with this racial trait count as outsiders with the native subtype and humanoids with the human subtype for any effect related to race, including feat prerequisites and spells that affect humanoids.

• And any shapechanger (like: Kitsunes, Skinwalkers or Doppelgangers) that takes the Human Guise feat:

You count as both human and your race for the purpose of taking character options, such as archetypes, feats, spells, traits, and prestige classes.

Keep in mind that planar half-breeds exist for non-human races, as pointed out in Blood of Angels (Aasimars) and Blood of Fiends (Tiefling). Such variants would be an exception to this, as pointed out on the sidebar of Blood of Angels, for instance:

Non-human aasimars have the same statistics as human aasimars with the exception of size. Thus a halfling aasimar is Small but otherwise possesses the same statistics and abilities as a human aasimar-the difference is purely cosmetic. Non-human aasimars do not possess any of the racial abilities of their base race. However, they are usually raised in the same cultural context as other members of their base race, and thus generally adopt the same fighting style as their peers, use the same types of weapons and armor, and study the same skills.

So from a rules-as-written perspective, an Aasimar that has an elf parent and takes Scion of Humanity would count as humanoid(native) and still count also as humanoid(human) instead of humanoid(elf).

But are also affected by any race-specific effects

This may sound strong, but keep in mind that this also affects race-specific effects or effects based on creature type, like the Bane special weapon property, or an Intelligent Magic Item that wishes to defeat/slay all members of a specific race.

A half-orc, for example, is both a humanoid(orc) and a humanoid(human) creature. Meaning that they are affected by both a Human-Bane weapon and a Orc-Bane weapon (luckily, bane doesn't stack). A half-elf would meet the requirements of crafting a Cloak of Elvenkind. And so on.