Humans and The Half-Races
Humans by and large are the most plentiful race. This is due to two incredible and yet disturbing factors. Firstly, humans have a shorter lifespan than the other races and a much more rapid reproductive ability.
Elves typically live to 300 and carry a child for 2 years before birth. There is also a ~5 year recovery period before an Elven woman can bear another child.
Dwarves live to 250 and carry a child for 1 year. Dwarves possess no recovery period, but socially rarely have more than a single child.
Gnomes, Fennic, Lizard folk, Halflings, and Teiflings often live to 200 with varying incubation periods all greater than 1 year.
Humans however rarely live to 100, and carry for only 9 months with no significant recovery period after the birthing. Socially it is common for Humans to raise 2-3 children on average, a number only surpassed by the Fennic who hatch 4-6 in a lifetime.
Secondly, Humans have the most flexible genome of all the races that share Meridian. This flexibility allows them to procreate with any of the other races to create “Half-” children.
These Half races are not technically 50/50 humans as their namesakes would imply, but rather a mule like offspring that shares traits of both while being neither. Depressingly, these half races have a high rate of sterility for reasons unknown. Those that can breed have been observed to create full blooded children of either race. Half races do not spawn half races. Half races also fail to possess the humans flexible genome, they are limited to breeding with other humans, a matching half race or wherever their other half comes from.
Mechanically, Humans and Half races are normal, as dictated by the 3.5 players hand book.