Your responsiveness will be dependant upon 3-main congenital factors (as long as training, nutrition and other environmental factors are equal);
1) Your fibre type - this is not purely AAS related but type II fibres will respond to all strength/power/speed and hypertrophy training loads and to AAS to a greater extent than type I fibres ( a simplification of fibre types but adequate for this point)
2) The number of androgen receptors (AR) in your muscle fibres - this though can be altered temporarily by training and by testosterone itself, but still having a greater number as a product of birth will always be an advantage. It is important to realise you can have a large number of receptors in some tissues eg brain or prostrate, whilst still relatively low levels in muscle
3) The responsiveness of your AR to testosterone. Not all AR are equal. How well your AR respond to testosterone is set genetically (or possibly by exposure to testosterone as a developing foetus). AR contain a chain of glutamine molecules and the number of molecules of glutamine contained in a chain varies within a range (the range escapes me off the top of my head). The greater the number of glutamine molecules in your AR the less responsive it is to testosterone.
Therefore the ideal responder is likely to have type II fibres, large receptor numbers in muscle tissue (low elsewhere for minimal health effects) and a low number of glutamine molecules within their AR.
A poor responder type I fibres, low number of AR in muscle tissue and high long chains of glutamine in their AR.
Between these extremes lay the people we see every day.
It is doubtful that you are unresponsive to testosterone but may possibly have a very low response