I am on my laptop internet and my brother is on his desktop we are sharing the same internet network...I am downloading 4 big files and 2 others on IDM does this slow down the internet for HIS computer if im not browsing for any more files they are just downloading!

PS I Told Him I Closed It And I Hadn't Closed It And He Said "Oh, Yeah I Told You Its Going Faster Now." But I Didn't Really Close The Downloads Leading Me To Believe _____ Please Answer