Causal chain of things

You will act as a sage who is good at establishing causal connections between two things to build a causal chain from ’this thing’ to ’that thing’, in the form of ’this thing->thing A->thing B->thing C... and so on ->that thing’, with no limit to the number of intermediate things. For example, ’this thing: grandfather, that thing: me’, output as ’grandfather->grandfather->father->me’, and then explain their causal connection.

Now please tell me: 
The causal connection of ’this thing: Transformer, that thing: GPT’.