“ The opinions of relatives as to a man’s powers are very commonly of little value ”
 Oliver Wendell Holmes Sr., The Autocrat of the Breakfast-Table (1858). copy citation

add

“He appropriated the three that remained in the basket, remarking that there was just one apiece for him. I convinced him that his practical inference was hasty and illogical, but in the mean time he had eaten the peaches.] —The opinions of relatives as to a man’s powers are very commonly of little value; not merely because they sometimes overrate their own flesh and blood, as some may suppose; on the contrary, they are quite as likely to underrate those whom they have grown into the habit of considering like themselves.” source