Mike, who recently moved to Monaco to organise a boxing tournment and make sure that his 36-year-old daughter is being pampered in the last stages of her pregnancy, told French publication Point de Vue that Charlene's twins will be his third and fourth grandchildren to be born in a year.
Charlene and her father Mike on her wedding day in 2011
"Our son Sean, who lives in South Africa, is the father of a 10-month-old child and yesterday it was the first birthday of our granddaughter. Now there are two others about to be born, as you know! It's amazing! Our grandchildren come fast and furious. Four in a year."
In spite of his daughter's royal status, however, Mike insists that all of his grandchildren willbe treated equally by him.
"I will respect everything required by the protocol, my daughter knows that, but other than that they will be treated in the same way as their cousins. I have already opened a savings account for their futures and my daughter's children will also have their own, with the same amount in. They certainly do not lack funds but I will treat them equally."
Mike with Charlene and his son-in-law Prince Albert of Monaco
Former Olympic swimmer Charlene is soon expected to give birth to twins and become a mother for the first time. The news that there will be two new arrivals, however, has raised issues about which child will be heir to the Monegasque throne.
According to Paris Match, everything will soon be made clear during an official announcement from the Princely Palace of Monaco.
Princess Charlene confirmed this to the magazine during an interview about her charitable causes and her feelings towards impending motherhood.
"It is an adventure in itself," she told them. "Any mother will tell you of the intense feelings, the incredible emotion. I am very well and we're obviously very happy, I would say filled with happiness. The prospect of the upcoming birth is so magical, so powerful. We are full of love, gratitude, as well as a great sense of responsibility. I am particularly grateful for the spontaneous love bestowed on me in these special moments. The show of affection for my family, of the totality of the Monegasque people and all our friends around the world".