The wife of Ben’s brother Tom has been battling cancer for three years and the family has now received the devastating news that the illness is terminal.
Ben Youngs was included in a 41-man squad for his second tour with the British & Irish Lions but this weekend informed head coach Warren Gatland of his decision to remain at home.
"We are a very close family and, as I am sure everyone can respect, time is now precious together," said Ben.
"The most important thing for me at this difficult time is to be able to offer as much support as I can to Tom and his family in the remaining time we all have together.
"It is a great honour to be selected as a member of the British & Irish Lions squad and I would like to thank Warren Gatland, the staff and the other players for their understanding in this situation. I wish them well and, like all rugby supporters in Britain and Ireland, hope they have a successful tour."
Tom and Ben will still play their part in the remainder of the season for the Tigers.
Both families hope their privacy can be respected at this difficult time. There will be no further comment from Tom, Ben or from Leicester Tigers at this point.
The British & Irish lions expressed their support for the Youngs family following the announcement that Ben has withdrawn from the squad for family reasons.
Head coach Warren Gatland said: "We fully understand and respect Ben's decision to stay at home. Family comes first and I know from having toured with Tom and Ben in 2013 how close they are.
“This is a difficult and important time for them and we send Ben, Tom and their family our heartfelt thoughts.”
Scotland and Gloucester Rugby scrum-half Greig Laidlaw will join the Tour party.