Parasexual
An offspring formed from more than a single parent, bypassing standard meiosis and fertilization; often occurs as a result of the fusion of two genetically unlike cells or nuclei.

Pedigree
A family tree diagram that shows how a particular genetic trait or disease has been inherited. 2. A diagram of genetic relationships and medical history in a family (also called family history). 3. A diagram showing the ancestral relationships and transmission of genetic traits over several generations in a family. 4. A diagram setting forth the ancestral history or genealogical register; may be used to determine the inheritance pattern of a particular trait.

Particulate
(as property of theory of inheritance) A synonym of atomistic.

Penetrance
The probability of a gene or genetic trait being expressed. "Complete" penetrance means the gene or genes for a trait are expressed in all the population who have the genes. "Incomplete" penetrance means the genetic trait is expressed in only part of the population. The percent penetrance also may change with the age range of the population.

2. In relation to autosomal inheritance, a term referring to the chance that a carrier of a mutant gene will manifest effects of that gene. When the penetrance is reduced, not everyone who inherits the gene will develop detectable features. 3. The proportion of individuals of a specified genotype that show the expected phenotype under a defined set of environmental conditions.

Pathological
Related to or caused by disease.

Path diagram A modified pedigree showing only the direct line of descent from common ancestors PCR Polymerase chain reaction is quick, inexpensive technique for making an unlimited copy of any piece of DNA sequences and is used often in gene testing techniques Parthenogenetic The ability to reproduce offspring without fertilization of the egg