A recent study has shown that those of us who’ve had a healthy childhood in terms of relationships can better handle relationships later in life. So, if you’ve had a good family life and you’ve got on well with siblings and parents then you’re going to be able to better understand the intricacies of relationships as you grow. Marriages will be easier for you and you’ll better be able to handle having a partner, it won’t be such a struggle to be with someone for you.
There’s a lot that we learn subconsciously which doesn’t even register on a conscious level at any point. We might not even think about how and why we react to things the way we do but the trust is that the smallest aspects of our childhoods alter the way we are on every level. It’s sometimes hard to see it but we’re all very much products of our upbringing and all of our upbringings are completely different. In that sense siblings who grew up in the same household will be totally different and react to other people differently as their upbringings, though similar, will not be the same.