I speak to my kids in Japanese mostly as well as my wife but we also speak to them in English. Both of our kids are considered behind their age group in English.
One of my friends spoke their son in Arabic, his wife spoke to their son in Japanese and they spoke to each other in English. They had to change that because their son wasn't speaking by age 3. Once they started speaking only English all the time, their son did great. Now he can speak all 3 no problem but as the doctor they took him to said "No wonder he isn't speaking, he's not sure what is going on!"
I speak to my kids in Japanese mostly as well as my wife but we also speak to them in English. Both of our kids are considered behind their age group in English.
One of my friends spoke their son in Arabic, his wife spoke to their son in Japanese and they spoke to each other in English. They had to change that because their son wasn't speaking by age 3. Once they started speaking only English all the time, their son did great. Now he can speak all 3 no problem but as the doctor they took him to said "No wonder he isn't speaking, he's not sure what is going on!"