Several inheritable traits or congenital conditions in humans are classical examples of Mendelian inheritance: Their presence is controlled by a single gene that can either be of the autosomal-dominant or -recessive type. People that inherited at least one dominant gene from either parent usually present with the dominant form of the trait. Only those that received the recessive gene from both parents present with the recessive phenotype. Mendelian inheritance (or Mendelian genetics or Mendelism) is a set of primary tenets relating to the transmission of hereditary characteristics from parent organisms to their children; it underlies much of genetics. ... For a non-technical introduction to the topic, see Introduction to Genetics. ... It has been suggested that dominant allele be merged into this article or section. ... It has been suggested that this article be split into multiple articles accessible from a disambiguation page. ... Individuals in the mollusk species Donax variabilis show diverse coloration and patterning in their phenotypes. ...

This mode of inheritance implies that the child of two parents that display the "recessive" phenotype should also display the "recessive" phenotype. Should this not be the case, that would be an indicator (but no proof) that one of the parents may not be the child's biological parent. A parent is a father or mother; one who begets or one who gives birth to or nurtures and raises a child; a relative who plays the role of guardian // Mother This article or section does not cite its references or sources. ... A paternity test is conducted to prove paternity, that is, whether a man is the biological father of another individual. ...

It also means the "recessive" phenotype may theoretically skip any number of generations, lying dormant in heterozygous individuals until they mate with someone who also has the recessive gene and both pass it on.

These traits include:

• Albinism
• Blood type
• Brachydactyly (Shortness of fingers and toes)
• Cheek dimples
• Cleft chin
• Earwax
• Face freckles
• Hallux / Morton's toe
• Hitchhiker's thumb
• Mid-digital hair
• Six fingers
• Widow's peak

Some traits were previously believed to be Mendelian, but their inheritance is (probably) based on more complex genetic models, possibly involving more than one gene. These include: Albinism (from Latin albus; extended etymology), more technically hypomelanism or hypomelanosis, is a form of hypopigmentary congenital disorder, characterized by a lack of melanin pigment in the eyes, skin and hair (or more rarely the eyes alone). ... Blood type (or blood group) is determined, in part, by the ABO blood group antigens present on red blood cells. ... Brachydactyly (Greek βραχί- = short plus δακτίλος = finger) is a medical term which literally means shortness of the fingers and toes (digits). ... For other uses, see Dimple (disambiguation). ... A cleft chin is unique trait resulting in a dimple on the chin. ... Wet-type human earwax on a cotton swab. ... Freckled twins: Predisposition to freckles is genetic and is related to the presence of the MC1R gene variant. ... The hallux or big toe is the biological name for digit I. In humans and non-human primates, the hallux is the largest toe on the foot. ... Sketch of Mortons toe, apparently common to the Celtic foot type. ... // This digit is one of the five fingers (though the word finger can also refer exclusively to the non-thumb digits). ... Sexdactyly is a genetic condition in which a person has six fingers on one or both hands, or six toes on one or both feet. ... Widows peak A widows peak is a descending V-shaped point in the middle of the hairline (above the forehead). ... A genetic disorder, or genetic disease is a disease caused, at least in part, by the genes of the person with the disease. ...

• Eye colour
• Hair colour
• Tongue rolling