Genasi can often be found in areas where the element they're associated with have the greatest influence (e.g. Waterborn in rainforests, Fire-Touched near volcanoes and hellholes, Earthborn in caverns and crevasses along the mountains, and Wind-Touched in arid deserts and rocky mountains where the wind blows strongest).
** plane(s) may or may not be involved with these experiments.
For GMs who want a quick and dirty conversion that doesn't require the features below, feel free to reflavor the Dragonspawn into the Fire Genasi, the Dwarf into the Earth Genasi, the Wood Elf as the Wind Genasi, and High Elves as the Water Genasi. For those who want more distinct mechanical differences, see below.
Common Genasi Racial Feats
(Champion Feat): You gain resistance to the element you're associated with equal to 1 + half your level. If your mix of two elements, the resistance you gain to both elements is one third your level. Any more, and you're getting only a fifth of your level in resistance, or none at all if the GM would consider your bloodline too thin to benefit from this feat.
GM Note: If you think the bloodline is too thin for the PC to benefit from it, don't let him get this at all (if he already took it, allow him to retrain it out without any hassles); also, while it's tempting to add a flaw with this feat that would render PCs vulnerable to damage of an opposing element, run that first with the players and see if they're alright with it (and maybe downgrade it to an adventurer feat if the rest of the group is fine with the flaw), otherwise assume that because the PCs are exceptional for their race, they have no downsides to taking this feat.
+2 DEX or CHA
Wind Dancer: Once per battle, you can roll 2d20 for any mobility-related stunt (such as leaping over pits) and pick either one as a result.
(Champion Feat): Once per battle as an interrupt, when a ranged attack is made against you, you can gain a +4 to AC and PD for that attack.
+2 STR or CON
Stone's Endurance: Once per battle as a quick action, you can spend a recovery to roll your recovery dice and gain temporary hit points equal to the result.
(Champion Feat): Once per day as a quick action, you gain resistance to normal weapons equal to your level until the end of your next turn.
Author's Note: I recommend that GMs who wish to introduce 4E Half-Giants/Goliaths in their campaign take this Genasi sub-race and reflavor them into Goliaths.
+2 DEX or INT
Burning Vengeance: Once per battle as a free action after taking damage from a melee attack, deal fire damage equal to your level to the attacker. This damage increases to twice your level at champion tier, and thrice your level at epic tier.
(Champion Feat): Each engaged creature takes damage from this ability, instead of just the attacker.
+2 DEX or WIS
Gentle Flow: Once per battle, you can pop free from any opponent as part of a move action and roll a normal save to avoid one attempt to engage you during your movement.
(Champion Feat): Once per day as a quick action, you can cause either yourself or an ally engaged with you to either spend a recovery or make a save against a save ends effect (but not both).
Stormborn and other Para-Genasi
+2 in any stat
Born of the Elements: Choose one of the racial powers associated with your parent Genasi races. You get that power. For example, a Stormborn is the child of a Wind-Touched and a Waterborn, so as a Stormborn you gain either Wind Dancer and Gentle Flow, but not both. Feel free to refluff the selected racial power to match the desired "hybrid" element (e.g. Stormbringer would be a refluffed Wind Dancer that is accompanied by peals of thunder and perhaps some rain water too, instead of just a gust of wind).
(Champion Feat): Once per day as a quick action, as long as you are able to use the racial power you've chosen, you can temporarily switch to a different racial power and use that power. This feat will allow you access to the feats of your second heritage's power.
Author's Note: The Champion feat basically allows you to switch racial powers, but does not allow you to use two racial powers in the same battle.