The pair's father Zizinho, a former professional player, revealed that his eldest son had been left devastated by his siblings snub for this summer's South Africa showpiece.
“Gio is very hurt and he wants to be at home with us," he said. “He is there now and he’s not well. We don’t know if he will play or not.”
Earlier in the week it had been reported that after being overlooked, younger sibling Jonathan dos Santos, 20, had decided to retire from international football with Mexico.
His father broke the news on Mexican television.
“Jonathan told me he is going to quit the Mexican team and I don’t want him playing for them anymore anyway,” he said.
“We are tired of how he has been treated. This is not the first time it has happened and it's enough for us. Jona won't ever play again for Mexico.”
Mexico had been training with a squad of 24 and had to cut one player to meet World Cup guidelines ahead of the tournament.
Jonathan has only played in friendly matches for Mexico to date and is therefore still eligible to play for both Brazil and Spain.
By Guy Ferneyhough
