The problem comes is the suggestion of travelling to destination X (in your case, the Bahamas) doesn’t just pop up out of thin air - friends may have travelled there recently, perhaps there has been a recent advertising push, etc.
Another family member looking up some destinations to travel, then speaking with you later - same external IP of the home wifi being reported, bam you get advertised the destinations they looked at the most.
Choosing a “random” topic again also doesn’t come out of thin air.
The problem comes is the suggestion of travelling to destination X (in your case, the Bahamas) doesn’t just pop up out of thin air - friends may have travelled there recently, perhaps there has been a recent advertising push, etc.
Another family member looking up some destinations to travel, then speaking with you later - same external IP of the home wifi being reported, bam you get advertised the destinations they looked at the most.
Choosing a “random” topic again also doesn’t come out of thin air.