Answer:

GENE

Answer	Crossword Clue
GENE	"Star Trek" creator Roddenberry
GENE	Kelly or Hackman
GENE	Mutation undergoer

GENE	Rayburn of game shows
GENE	Trait carrier
GENE	Character builder
GENE	Chromosome part
GENE	Hereditary character marker
GENE	Hereditary factor
GENE	Producer Roddenberry
GENE	Subject of some engineering

GENE	Trait determinant
GENE	Tunney or Tierney
GENE	Basic unit of inheritance
GENE	Chromosome component
GENE	Inheritance
GENE	Inheritance factor
GENE	Tierney or Kelly
GENE	Hereditary unit

GENE	Subject of passing concern?
GENE	Unit of heredity
GENE	Actor Wilder
GENE	DNA structure
GENE	Decides looks
GENE	Kind of pool
GENE	Mendelian unit
GENE	Wilder

GENE	Chromosome unit
GENE	Kelly's inheritance?
GENE	Trait transmitter
GENE	Pool unit
GENE	Tierney or Tunney
GENE	Trait's cause, maybe
GENE	Trait maker
GENE	Roy's peer in cowboy crooning

GENE	Lender of a trait
GENE	One in a pool?
GENE	Allele
GENE	Part of an inheritance
GENE	Pool member?