In genetic family trees the male sex is usually represented by a square and the female by a circle. Crossings are indicated by horizontal lines that connect squares to circles and their direct offspring are listed below and  connected to that line. The presence of the studied phenotypical form is indicated by a complete hachure (shading) of the circle or the square correspondent to the affected individual. It is useful to enumerate the individuals from left to right and from top to bottom for easy reference.