On a pedigree diagram, two symbols are joined by a horizontal line, and vertical lines lead down from it to three further symbols. What does this show?

Explicación

A horizontal line between two symbols marks a couple who have children together, and each vertical line running down from it leads to one of those children, drawn a row lower to show the next generation. Reading the joined pair as a brother and sister ignores that children are placed below their parents rather than beside them.