Cousins in the fourth degree are connected by causation, if I may be allowed to use that term; but not so closely as brothers, much less as child and parent.

In general we may observe, that all the relations of blood depend upon cause and effect, and are esteemed near or remote, according to the number of connecting causes interposed betwixt the persons.
Of the three relations above-mentioned this of causation is the most extensive.

Two objects may be considered as placed in this relation, as well when one is the cause of any of the actions or motions of the other, as when the former is the cause of the existence of the latter.

For as that action or motion is nothing but the object itself, considered in a certain light, and as the object continues the same in all its different situations, it is easy to imagine how such an influence of objects upon one another may connect them in the imagination.
We may carry this farther, and remark, not only that two objects are connected by the relation of cause and effect, when the one produces a motion or any action in the other, but also when it has a power of producing it.

And this we may observe to be the source of all the relation, of interest and duty, by which men influence each other in society, and are placed in the ties of government and subordination.