Human

Basic Information

Genetics and Reproduction

Other Species

Elf > Half-elf
Half-elf > 50% chance Human, 50% chance Half-elf
Orc > Half-orc
Half-orc > Half-orc
Dwarf > Dwarf 
Gnome > Halfling
Dragons > Dragonborn (Dragon magic required)
Fiends > Tiefling
Tiefling > Tiefling