It is often observed that identical (i.e. monozygotic) twins tend to get along well. After all, they have the same DNA, having come from fertilisation of a single egg by a single sperm, with the fertilised egg then split to become them. In terms of the Dharma, for two sentient beings to born together so closely means they should have created very similar karma together, while being physically attached to each other in their immediate past lives.
Beyond looking alike, just born twins are likely to habitually think alike too… till differences creep in via unique experiences, which alter perceptions and choices, in turn changing character. Perhaps that worse than sibling rivalry is twin sibling rivalry. Imagine being driven apart by competition, with this question haunting the mind of the ‘weaker’ – ‘If we were born “alike”, why is s/he doing better than me?’
If there is inadequate joy for the other’s achievements, such jealousy is likely to grow if one twin cannot seem to catch up with the other. Here arises a real-life doppelganger horror story, always seeing a better version of your’self’, whom you cannot seem to match. Instead of just bettering oneself, there is constant reminder that there is already a better ‘version’, whom seems so close yet so far.
Lacking equanimous rejoice, there might be jealousy of those better. Lacking equanimous empathy, there might be gloating at those not doing better. The only truly relevant race is to keep outdoing oneself, not anyone else, whether they seem ‘similar’ or not. May we work towards realising non-self, while encouraging others to do so too. Why become worse, more self-centred version of our’selves’?