Dear Sarah,

Disclaimer: I am not a psychotherapist or have any training in Psychology, just a participant reading here and giving my personal insights.

I think from what you are describing you might have developed some defense mechanisms as a child. Maybe you felt that you parents had no time or attention for you, or they did but not as much as you needed, so you became detached and cold to counter that. Something like, “ok well I don’t need or want you either, I can manage on my own”.
It seems that now as an adult you somehow repeat your parents’ behavior with you towards other people – you only take care of the material side of things, giving presents or money, as I can imagine that your parents clothed and fed you, but the emotional part is lacking.

I am sure you are not really a mean and cold person inside, and if you present such behaviors it is probably because as a child you developed them as a strategy to defend yourself from feeling unwanted and hurt.