The Bible does not specifically say we will know our family and friends in heaven, but there are a few implications that we may recognize one another. For believers, it will be our great joy to see those we loved on earth; however, the greatest joy will be found in our relationship with our Savior Jesus Christ. Heaven is all about Jesus and His redeeming love for us. Our worship and the wonders of heaven will be all the more sweet because we can praise and worship in the company of other Christians, especially those whom we loved and enjoyed on earth.
One of the most blessed parts of heaven, for believers, will be the presence of their believing loved ones—family and friends who have gone on to be with the Lord before us. It seems reasonable to think that we will be able to see, know, and spend time with one another for all eternity, although our primary joy will be in doing those things with our blessed Lord and Savior.
Although the Bible doesn't have many references to seeing and recognizing others in the afterlife, there are a few. David assumed that he would be able to recognize his son in heaven, not a generic soul indistinguishable from all other souls. The rich man could see Lazarus at Abraham's side, although there was a great chasm fixed between them. When Jesus fully revealed Himself, the disciples recognized Him with His glorified body.
Many people say they can't imagine heaven without their loved ones who have died without Christ. But heaven will not be one iota less joyful if those we loved on earth are not all present. Heaven's greatest joy will be to be in the presence of God whom we can love and adore without the sin that hinders that relationship now. Worshiping our Lord and Savior will be sufficient bliss to last an eternity, and it will be a joy to know Him and be known by Him and those with whom we worship.