Matthew 12:47

‘And one said to him, “Behold, your mother and your brothers are standing outside, seeking to speak to you.” '

Someone comes and tells Jesus that his mother and brothers are outside wanting to speak to Him. According to Jewish custom this would be seen as a primary matter. Family loyalty was considered to be extremely important. The natural reading here is to see these as His younger brothers. (Had they been elder step-brothers it would have invalidated the claim in Matthew 1:1. It was only dogma that centuries later suggested otherwise. It is clear that neither Matthew nor the other Gospel writers had any problem with the thought of Jesus having brothers).