"The people who slander others are often brethren."
"The perpetrators of abuse are often brethren."
"the perpetrators of ~" 「〜の犯人」
"abuse" 「誹謗中傷」
"are often ~" 「〜の場合が多い」
"brethren" 「同業者」
"The people who slander others are often brethren."
"the people who slander others" 「他の人を誹謗中傷する人は」