It has been noted from the past that the price of altcoins follows the price of the bitcoin that means when the price of bitcoin is high then the price of altcoins rise high. Actually this relationship is not proved by any research but it is built on the basis of the previous experience.
Yes, you are right,
All coins are related to Bitcoin, all types of coins are of course related to Bitcoin, altcoin rises because of bitcoin, down altcoin because of bitcoin, actually this is what we have to do research to find out the altcoin relationship with bitcoin.