It really depends on how the advertising server are serving the adverts - it could be based on IP tracking, in which case the only way to avoid it would be to use a separate connection, in this case meaning a VPN, Tor, a mobile hotspot etc. If other devices are using the same account, such as the same Google, Facebook, or Microsoft account, then that would provide another method for determining devices are the same person, but you say that isn't the case. There is also the possibility that you have installed adware inadvertently which has infected other devices on your network, but if they are different OSes and everything is up to date this is probably least likely.
There is also the possibility that it's a coincidence. You all live in the same area, may have similar interests, and it is the new year, so showing new year journals might not mean anything. When it comes to birthdays/holidays though you may want to utilise VPN and private browsing.