Related, cognate, kindred, allied, affiliated can all mean connected by or as if by close family ties.
Related, when referred to persons, usually implies consanguinity, but sometimes implies connection by marriage.
When applied to things, related suggests an often close connection, the particular nature of which is to be gathered from the context.
Cognate differs from related chiefly in being referable only to things that are generically alike or that can be shown to have a common ancestor or source or to be derived from the same root or stock.
Kindred, in its primary sense, stresses blood relationship. In its more common extended sense, it implies such likenesses as common interests, tastes, aims, or qualities that might be characteristic of a family. When the reference is to persons, congeniality is usually connoted.
When applied to things, a more obvious connection or a closer likeness is implied than in related .
Allied more often implies connection by union than by origin, and especially by marriage or by voluntary association. It often connotes a more remote family connection than related .
In its extended use it usually stresses relation based on the possession of common characters, qualities, aims, or effects which lead either to union or to inclusion in the same class or category.
Affiliated also stresses connection by union, but it may imply a dependent relation such as that of a child to a parent. Sometimes it implies the adoption of the weaker by the stronger.
Sometimes it connotes a loose union in which the affiliating units retain their independence, but derive support or strength from the main, central, or parent body, or cooperate in its work.