Less liable to open manifestation is the corresponding transfer of affect from parent to parent-in-law where the emotion concerned is love rather than hatred. Such a transfer may nevertheless occur in certain circumstances. In a positive form it may result in a high degree of veneration or affection for the parents-in-law (or one of them), which--especially if it should coincide with a high degree of parent love in the other partner to the marriage--may lead to the existence of very friendly and intimate relations of the younger couple with the elder; relations which may, however, in many cases, tend to undermine the initiative and independence of the younger pair. In a negative form (which is very liable to occur, since the vigorous repression of the original incestuous thoughts very easily extends to any fresh tendencies calculated to arouse them) a transfer of this kind may lead to frequent troubles, misunderstandings and frictions between the child-in-law and parent-in-law whom it concerns. [Sidenote: Corresponding displacement on the part of the parents-in-law themselves] The third and last of our three factors which complicate the relations of children-in-law and parents-in-law consists in a similar displacement of affect on the part of the parents-in-law, in virtue of which they may direct towards their children by marriage the affection or hostility which they originally experienced in relation to their own children; a factor the significance of which may perhaps be more fully and easily appreciated after we have discussed the intimate nature of these original feelings of parents to their own children (_cp._ Ch. XIV below), and with regard to which perhaps it is therefore best to content ourselves with a mere passing reference here. [Sidenote: Son-in-law and Mother-in-law] The relation between child-in-law and parent-in-law which has become notoriously the most difficult in recent times is that of son-in-law and mother-in-law. This relation too has been made the object of some special study by psycho-analysts[110], who have found in it all the factors which we have referred to above. Among the most important grounds for the hostility which so often marks this relationship have been observed the following:--