Sri Aurobindo
Letters of Sri Aurobindo
Volume 2. 1934 — 1935
The question put to me was whether it was possible for one to love another’s child as well as one loved one’s own children. To that of course there can be only one reply that it is perfectly possible, for it often happens. It is even possible to love another’s child better than one’s own. I don’t think it can be said that in all these cases the equal or greater love is an illusion. Where it is an illusion (the cases you quote), it is because the thinking mind has influenced the vital feeling; the stepmother knowing that it is her duty to care for all equally, helped perhaps by a psychic strain in her emotions, comes to believe or imagine (without any hypocrisy but not without some involuntary self-deception) that her love is equal for all. When it comes to the test the genuine vital attachment for her own prevails over the lesser vital attachment for the one who is not her own; the vital reveals itself as the deciding factor and the mental element and the psychic strain are unable to prevail against it. But where the love for the other’s child is itself vital, not based on a mental ideal, and is truly intense, the same result would not follow. Again if there is a strong psychic affinity between the man or woman and the child not his or her own by birth and this has been seconded by an equally strong vital pull, the resultant love would reveal itself as intense and genuine and the more ordinary love would not prevail against it.
Of course, these cases are not in the majority. Ordinarily the family feeling and sense of [ownness] would be stronger. But if we ask why, I doubt the answer that it is because of the bodily parentship, the animal fact of the child being from the mother’s own womb. In reality the animal mother will bring 
up a substituted little one (alone or with the others) as tenderly and carefully as if it had been from her own womb, it will often so bring up even one of another species. If an alien human infant were substituted for the real one in the cradle without the mother knowing it the result would not be different. Therefore what counts is an idea, feeling, imagination in the vital mind that this is “mine” and an instinctive vital attachment created by it along with the love and affection that grows up in the very act of nursing and bringing up a clinging and dependent creature. This in human beings gets farther strengthened by the mental idea of the lasting family tie which prevents the relation from being evanescent as in the animal creation. All that creates a very powerful saṃskār which has become automatically effective and tenacious. It is natural that in a majority of cases, it should be stronger than a tie not supported by all these things together. And the human vital, even if it follows the ordinary groove, is not limited by it and it has a power of free play according to its fancy or impulsion which makes for it many other lines than the ordinary one.